I. Field
The present invention relates generally to telecommunications, and, more specifically, to power savings in wireless devices employed in wireless communication systems and cellular communication systems.
II. Background
A modem communication system provides data transmission for a variety of applications, including voice and data applications. In point-to-multipoint communications, modem communication systems have been based on frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and other multiple access communication schemes.
A CDMA communications system is typically designed to support one or more CDMA standards, such as (1) the “TIA/EIA-95 Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (this standard with its enhanced revisions A and B may be referred to as the “IS-95 standard”), (2) the “TIA/EIA-98-C Recommended Minimum Standard for Dual-Mode Wideband Spread Spectrum Cellular Mobile Station” (the “IS-98 standard”), (3) the standard sponsored by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents known as the “W-CDMA standard,” (4) the standard sponsored by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in a set of documents including “TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems,” the “C.S0005-A Upper Layer (Layer 3) Signaling Standard for cdma2000 Spread Spectrum Systems,” and the “TIA/EIA/IS-856 cdma2000 High Rate Packet Data Air Interface Specification” (the “cdma2000 standard” collectively), (5) the 1xEV-DO standard, and (6) certain other applicable standards. The standards expressly listed above are incorporated by reference as if fully set forth herein, including annexes, appendices, and other attachments.
Evolution-Data Optimized (EV-DO) is a wireless telecommunications standard used for transmission of data for broadband Internet access. EV-DO uses code division multiple access, or CDMA, as well as time division multiplexing, or TDM, to maximize individual user throughput and overall system throughput. EV-DO represents an evolution of the CDMA (IS-2000) standard supporting increased data rates and are optimized for data transmission. EV-DO is typically deployed together with voice services. In such a system, voice may be transmitted as data, for example, in voice over internet protocol (VoIP) transmissions.
The aforementioned 1xEV-DO includes Revision 0, Revision A, and Revision B, each of which provide benefits over previous versions of EV-DO. Capacity and quality of service (QoS), for example, are improved in 1xEV-DO Revision A. Revision B allows multi-carrier device operation.
Generally, a base station (in all versions of EV-DO, called an AN, or Access Network) provides data on the downlink to a user's access terminal (AT). The transmission of large quantities of data from the AN to an AT can sometimes result in the AT remaining fully powered for extended periods of time due to the bursty nature of the transmission and uncertainty as to whether all data has been received from the upstream devices. Such devices do not efficiently use power, and as a result power can rapidly drain from the device.
In wireless DO networks, an AT may be in a traffic state/mode or in a dormant state/mode. In the traffic state, the DO network allocates air link resources for communication between the AT and the AN at the AN. In the dormant state, the traffic channel is torn down, and air link resources are powered off at the AT. Power required to operate these resources is consequently conserved during the dormant state, thus extending battery life at the AT. Other subsystems of the AT may also be powered off or put into a “power save” mode for most of the time during the dormant state. The AT then occasionally “wakes up” to listen to the paging channel of the wireless system in order to respond to incoming pages or communication requests received from the AN. The duty cycle of such periodic paging channel checks is low to reduce the stand-by power consumption.
For a given battery capacity, the rate and amount of power consumption determines the amount of AT operation that may occur without recharging. Another way of looking at power consumption is that for a given AT operating time between battery recharges, average power consumption dictates the required battery capacity and, consequently, the size, weight, and cost of the battery. Reducing power consumption of an AT results in lower battery requirements and can save costs.
The present EV-DO specification limits what can be done with respect to AN operation and conserving power. EV-DO AN transmissions must occur in a certain predetermined manner, and thus techniques such as sending special power saving indications from the AN to the AT or transmitting data from the AN only at certain times or under certain conditions are generally unavailable.
Therefore, there is a need for methods and apparatus that would reduce power consumption of ATs. There is also a need for methods and apparatus that would reduce power consumption of ATs without excessively compromising performance characteristics of the access terminals and of the radio networks with which the terminals communicate. There is a further need for effectively and efficiently operating in in-place or previously-deployed networks while simultaneously providing reduced AT power consumption, and minimizing or eliminating required hardware changes to the radio network.